INDIANAPOLIS — Indianapolis Motor Speedway officially opened for the month of May with a chaotic road course race that started with a wreck, saw James Hinchliffe and the mayor of the city injured by flying debris, and, finally, Simon Pagenaud celebrate a fuel-mileage victory.

Pagenaud won the inaugural Grand Prix of Indianapolis on Saturday, the first IndyCar Series race on IMS’ road course, by stretching his fuel the final 29 laps.

The Frenchman was one of several drivers to gamble on gas, and he took the lead when Oriol Servia had to stop with four laps remaining. Pagenaud managed to make it to the finish for his third series victory despite having to keep an eye on his mirrors.

Ryan Hunter-Reay was second and Helio Castroneves third. Sebastien Bourdais and Charlie Kimball rounded out the top five.

Hinchcliffe was taken from the track on a stretcher and transported to a hospital, where he was diagnosed with a concussion after he was hit in the head with debris. A replay appeared to show debris from a car in front of him flew into his cockpit following a restart.

IndyCar said he’ll have to be re-evaluated before he’s cleared again to drive. Preparations begin Sunday for the Indianapolis 500, with qualifying scheduled to begin next Saturday for the May 25 race.

IndyCar policy in the past has been to hold a driver with a concussion out of the car a minimum of seven days.

Andretti Autosport said EJ Viso will be the standby driver for Hinchcliffe.

“I’m a little stiff and sore and I’d love to be back in the car tomorrow, but I suppose I should probably let the doctors make that decision,” Hinchcliffe said in a statement.

Hunter-Reay said he drove by Hinchcliffe’s car and couldn’t figure out what happened.

“I was actually next to him on track and all of a sudden debris went everywhere and he slowed up,” Hunter-Reay said about his teammate. “It was something that happened in front of him and he was hit.”

The race began with a violent wreck when pole-sitter Sebastian Saavedra stalled on the standing start. He was hit by multiple cars, and debris struck Indianapolis Mayor Greg Ballard as he waved the green flag.

Saavedra’s car simply didn’t go when the lights went out and, after Hunter-Reay frantically darted around him, Saavedra was clipped by Carlos Munoz and then hit hard from behind by Mikhail Aleshin.

“We just followed protocol at the start,” Saavedra said. “As soon as I released the clutch, it went from 11,000 rpm to zero. This should not have happened, unfortunately.”

The initial hit from Munoz didn’t seem too bad, but Aleshin’s direct hit sprayed debris all over the track, sending spectators and track workers standing along the wall scrambling for cover.

Saavedra was visibly upset after the accident as he talked to his team on his pit stand. He had won the first pole of his career — in part because Hunter-Reay had his two fastest laps disallowed for causing a caution in Friday’s qualifying — and was looking for a strong finish at the famed race track.

“Man, we had an opportunity to be at the front of the pack in this amazing place. We wanted to bring it home in the same place,” he said.